1. Field of the Invention
A thin film transistor and a method of manufacturing the thin film transistor are provided. More particularly, example embodiments relate to a thin film transistor having improved driving characteristics, and to a method of manufacturing the thin film transistor.
2. Description of the Related Art
In general, a display panel includes a display substrate including a switching element driving a pixel, and an opposing substrate facing the display substrate. The switching element may be a thin film transistor. The thin film transistor includes a gate electrode, a source electrode, a drain electrode and a semiconductor pattern forming a channel electrically connecting the source electrode to the drain electrode. The semiconductor pattern usually is formed from amorphous silicon (a-Si), poly-silicon (poly-Si), or oxide semiconductor.
An amorphous silicon layer may be easily formed on a large-sized substrate. However, because electron mobility of the amorphous silicon layer is about 0.5 cm2/Vs, the amorphous silicon layer has low driving characteristics. A polysilicon layer, on the other hand, has an electron mobility in the range of 10 to hundreds of cm2/Vs, which is greater than that of the amorphous silicon layer. However, to form the polysilicon layer a process of crystallizing an amorphous silicon layer must be performed. Thus, it is difficult to form the polysilicon layer uniformly on a large-sized substrate, and manufacturing costs for forming the polysilicon layer are high.
As the size of display devices increase, the length required for signal lines increases, and electrical resistance also increases. The increase in electrical resistance causes RC signal delay. To solve the above problem, the signal line may be formed from a material having a low electrical resistance. However, available materials that have the appropriate physical and electrical characteristics are limited. In order to prevent RC signal delay, the time required to charge a pixel with a voltage must be reduced. Thus, the electron mobility of the semiconductor pattern of the thin film transistor driving the pixel needs to be high. However, it is difficult to form a polysilicon layer uniformly on a large-sized substrate, and an oxide semiconductor has a relatively low reliability.